An air bearing slider is often employed in magnetic disk drives, for example. The slider is capable of flying above the disk surface of the magnetic disk when it receives an air stream generated along the disk surface during rotation of the magnetic disk. The air bearing slider allows a transducer element (which is embedded in the slider body to oppose the disk surface) to achieve read/write operations upon the magnetic disk without contacting the disk surface.
The air bearing slider is usually supported at the tip end of a carriage arm. When the carriage arm swings around its support axis, the air bearing slider is allowed to cross recording tracks on the disk surface in the radial direction of the magnetic disk. This movement of the slider allows the transducer element to be positioned above a target recording track on the disk surface.
When the swinging movement of the carriage arm is employed to position the transducer element, it is impossible to maintain the air bearing slider in a constant orientation with respect to the tangential direction of the recording tracks. As the slider moves in the radial direction of the magnetic disk, the slider varies its orientation with respect to the recording tracks. Accordingly, the slider receives the air stream from somewhat different directions as it moves in the radial direction. This variation in the direction of the air stream causes variations in the flying height of the slider above the disk surface. It should be noted that throughout this specification the distance between the slider and the disk surface will be referred to as the flying height above the disk surface. However, such xe2x80x9cflying heightxe2x80x9d also refers to the distance between the slider and the disk surface in sliders flying below the disk surface.
If larger variations are caused in the flying height of the slider, the increment of the height above the lowest flying level of the slider must be increased. In particular, such an increased increment at the rear rail in which the transducer element is embedded causes the transducer element to be farther separated from the disk surface, and weakens the sense of the transducer element in read/write operations. This leads to a disadvantage in attempts to improve the recording density of the magnetic disk.
It is accordingly an object of the present invention to provide an air bearing slider capable of reducing to the utmost the variations in the flying height of the slider, irrespective of its movement along the radial direction of the storage disk.
Briefly, the present invention relates to an improved air bearing slider in which variations in its flying height are reduced, even as it travels radially across a disk. The present invention also relates to a disk apparatus employing such a slider, as well as to the method for manufacturing such a slider.
More specifically, the present invention relates to an air bearing slider that includes a front air bearing surface formed on a bottom of a slider body near an upstream end thereof, a rear air bearing surface formed on the bottom of the slider body near a downstream end thereof and a front raised surface formed upstream of the rear air bearing surface. The front raised surface has a level that is higher than that of the rear air bearing surface. The slider also includes a front wall that extends between an upstream end of the rear air bearing surface and a downstream end of the front raised surface and at least one side wall that extends between a side edge of the rear air bearing surface and the bottom of the slider body without being interrupted by a step. Note that the term xe2x80x9cstepxe2x80x9d is defined, throughout the specification and claims, to exclude a step which fails to reach a level high enough to contribute to an increase in the positive pressure generated at an air bearing surface when the air bearing slider receives the air stream.
With the above structure, a larger positive pressure or lift can be generated at the rear air bearing surface when the rear air bearing surface receives an air stream flowing along the front raised surface and the front wall during rotation of the storage disk. Since no raised surface adjacent the rear air bearing surface is formed on the side wall, the air stream, which may travel in different directions, will always reach the rear air bearing surface through a constant area of the front raised surface and the front wall. Accordingly, variations in the direction of the air stream fail to cause variations in the positive pressure at the rear air bearing surface, so that variations in the flying height of the slider can be reduced to the utmost, irrespective of the movement of the slider in the radial direction of the storage disk.
The air bearing slider of the present invention may further include a second rear air bearing surface, which, when combined with the rear air bearing surface mentioned above, forms a pair of rear air bearing surfaces, which are both positioned near a downstream end of the slider body. This pair of rear air bearing surfaces creates a pair of positive pressures near the downstream end of the slider body that contribute to stabilizing the behavior of the air bearing slider during flying.
One preferred embodiment of the present invention further includes a second front raised surface formed upstream of the second rear air bearing surface, with the second front raised surface having a level that is higher than that of the second rear air bearing surface, as well as a second front wall that extends between an upstream end of the second rear air bearing surface and a downstream end of the second front raised surface. This embodiment may further include side raised surfaces formed on both sides of the second rear air bearing surface, wherein the side raised surfaces extend in opposite lateral directions at a level that is higher than that of the second rear air bearing surface, as well as a set of second side walls that extend between lateral edges of the side raised surfaces and the second rear air bearing surface. With this additional structure a larger positive pressure or lift can be generated at the second rear air bearing surface, as well as at the above-mentioned first air bearing surface, when the second rear air bearing surface receives an air stream flowing along the second front raised surface and the second front wall during rotation of the storage disk.
The air bearing slider may further include a third front raised surface formed upstream of the front air bearing surface that has a level that is higher than that of the front air bearing surface, and a protrusion formed on the third front lower surface that has a tip end that is lower than the level of the front air bearing surface. The protrusion serves to avoid direct contact between the front air bearing surface and the disk surface of the storage disk when the slider body is seated on the disk surface, so that there is less adhesion between the lubricating agent or oil spread upon the disk surface and the slider body. Accordingly, the slider body can more easily take off from the disk surface at the beginning of rotation of the storage disk.
The air bearing slider may further include a front rail formed on the bottom of the slider body at an upstream position so as to extend in the lateral direction and to define the third raised surface and the front air bearing surface on its top surface, first and second side rails extending from opposite lateral ends of the front rail toward the first and second rear air bearing surfaces, respectively, so as to define top surfaces that are on the same plane as the third raised surface of the front rail, a first rear protrusion formed on the top surface of the first side rail that has a tip end that is lower than the level of the first rear air bearing surface, and a second rear protrusion that is formed on the side lower surface and has a tip end that is lower than the level of the second rear air bearing surface. With this structure, a larger negative pressure can be generated within an area surrounded by the front rail and side rails. The larger negative pressure can be balanced with the larger positive pressure at the first and second rear air bearing surfaces in order to better stabilize the behavior of the air bearing slider during flying. Moreover, the first and second rear protrusions serve to prevent the first and second rear air bearing surfaces from directly contacting the disk surface of the storage disk when the slider body is seated upon the disk surface, so that there is less adhesion between the lubricating agent or oil spread over the disk surface and the slider body. Accordingly, the slider body can more easily take off from the disk surface at the beginning of rotation of the storage disk.
In a second embodiment, the second rear air bearing surface may be configured differently so that it lacks a set of side raised surfaces. In this embodiment, the second set of side walls extend directly between the lateral edges of the second rear air bearing and the bottom of the slider body without being interrupted by a step. With this structure, it is also possible to reduce variations in the flying height of the slider body irrespective of the movement of the slider body in the radial direction of the storage disk in much the same manner as the above mentioned first rear air bearing surface.
When the aforementioned air bearing slider is produced, the method preferably includes the steps of forming a resist of a first pattern on a wafer for defining a contour of an air bearing surface with a margin adjacent the contour of the air bearing surface in a lateral direction of a slider body, removing part of the wafer around the resist of the first pattern, forming a resist of a second pattern on the wafer for defining the contour of the air bearing surface with an additional area covered upstream of the air bearing surface, and removing part of the wafer around the resist of the second pattern so as to shape the air bearing surface.
When the air bearing surface is shaped according to the second pattern, a portion corresponding to the margin defined by the first pattern is removed adjacent the air bearing surface. As a result, no step is formed adjacent the air bearing surface in the lateral direction of the slider body. On the other hand, the covered additional area serves to shape a step upstream of the air bearing surface in the slider body. With this method, even if the second pattern is offset with respect to the first pattern, no step is formed adjacent the air bearing surface in the lateral direction of the slider body. The aforementioned air bearing slider can reliably be provided.
The method may further include the steps of forming a resist of a pad pattern on the wafer, before forming the resist of the first pattern, for defining a contour of an adhesion prevention pad with a margin around the contour of the pad, removing part of the wafer around the resist of the pad pattern so as to shape a first material, defining a margin around the contour of the pad on the first material in forming said resist of the first pattern, shaping a second material out of the first material in removing part of the wafer around the resist of the first pattern, defining the contour of the pad on the second material in forming said resist of the second pattern, and shaping the contour of the pad in removing part of the wafer around the resist of the second pattern.
When the second material is shaped out of the first material, and when the contour of the pad is shaped out of the second material, portions corresponding to the margins defined by the pad pattern and the first pattern are removed around the contour of the pad. As a result, no step is formed around the pad.
It should be noted that the air bearing slider of the present invention may be employed in hard disk drive units (HDD), as well as in other types of storage disk drives.